Manufacture of miniature thermionic devices



May 14, 1946. v F. R. KEW ET AL 2,400,122

MANUFACTURE OF MINIATURE THERMIONIC DEVICES Fil ed June 25, 1943 2Sheets-Sheet 1 7 IN VENTORS jfi A/v/r f2 KEW.

BY 2 e/bSEPH JBA/VNOM May 14, 1946. F. R. KEW ET AL 2,400,122

MANUFACTURE OF MINIATURE THERMIQNIC DEVICES Filed June 25, 1945 2Sheets-Sheet 2 A TTORNE Y5 Patented May 14, 1946 MANUFACTURE OFMINIATURE THERMIONIC DEVICES Frank R. Kew, Bloomfield, and Joseph JamesBannon, J r., North Arlington, N. .L, assignors to Tung-Sol LampWorks,Inc., Newark, N. J., a

corporation of Delaware Application June 25, 1943, Serial No. 492,218

' 15 Claims. (Cl.'2 50 -27.5)

This invention relates to the manufacture of thermionic devices.

In the manufacture of thermionic devices, and particularly miniaturedevices, the assembly of the elements is usually a tedious operationrequiring skilled labor and involving large expense and an unduly'largepercentage of rejects. For example, one of such tedious operations isthe assembly of direct emission filaments for miniature mounts, whichare made of extremely small wire and are required to be inserted intoand accurately positioned in the miniature grids.

One object of the'invention is a novel and improved method of assemblyof these small direct emission filaments in miniature mounts.

A further object of the invention is a novel means and apparatus forfacilitating such assembly.

Further objects of the invention'will hereinafter appear.

For a better understanding of the invention reference may be had to theaccompanying drawings wherein:

Fig. 1 isa side view partly in section of a novel apparatus embodyingthe invention;

Fig. 2 is a view of the same taken at right angles to Fig. 1;

Fig. 3 is a view taken on the line 3-3 of Fig. 1;

Fig. 3a is a perspective view illustrating a modification of a part ofthe apparatus;

Fig. 4 is a sectional view of a miniature mount to which the inventionis applicable;

Fig. 5 is a view at right angles to Fig. 4;

Fig. 6 is a sectional view along the lines 6-6 of Fig. 4; r

Fig. 7 is a sectional view along the line 1-1 of Fig. 4; and

Fig. 8 is an enlarged perspective view of a part of the apparatus.

We have illustrated the invention as applied.

to the assembly of direct emission filaments in miniature mounts, but itis understood that this is for illustrative'purposes only and thatcertain features of the invention are of more general application.

This mount is shown on an enlarged scale in Figs. 4-8 for purposes ofillustration. It comprises concentric cylindrical plates I and 2, withmica or other insulating discs 3 and 4 fastened at the bottom and top ofthese plates respectively and holding them in concentric relation. Theparticular means of fastening is omitted for convenience inillustration. The device comprises a -multi grid structure, there beingthree such grids -5, 6 and l. The grid 5 is carried by the posts or.

cost is unduly large.

wires 8, the grid 6 by the'wires 9, and the grid 1 by the wires to.These wires project through openings formed in the discs 3 and 4 and aredisposed inthe same plane. The grid structures are oval-shaped-incross-section and are concentric with each other, though thecross-section of the outer grid 5 more nearly approaches a circle.

In addition to the elements above described the device comprises adirect emission filament H :disposed within the innergrid I. Thesefilaments H are so fine and small that they can be assembled with onlythe greatest care and skill according to the conventional practices andeven with the most careful and skillful operations the reject percentageis quite large and the labor Our invention resides in an improved methodand means for introducing these very fine filaments H into and throughthe 0 very small inner grids I. 2 1

The loading means comprises a funnel-shaped member I5 open at the top l6for the reception -of the fine emission filaments H. The outlet for thefunnel is a small cylindrical bore H.

The funnel member I5 is provided with a slot l8 extending throughout itslength from top to bottom and parallel to the funnel axis, this slotextending all the way through the wall of the member to the opening orfunnel-shaped chamber in the center. The slot walls are flared at theirupper ;ends as'indicated at l8 for a purpose hereinafter described.

At the base of the funnel there is attached an aligning or locatingelement 20 which maybe formed integrally with or as a separate. elementfrom but fastened to the funnel, and the cylindrical bore ll continuesthrough this element. This element is constructed so as to center thefunnel with the cylindrical bore I! over a centrally disposed V-shapedopening 4' in the top :mica disc 4. The slot 18 is continued throughthis element. 20, so as to allow the filament to be released from theloading device. 'The under side of the, element is a planesurfacedisposed at "right angles to the'axis of the funnel and in theassembling or loading operation the element 20 rests directly uponthetop mica or shield disc 4. The element 20'is provided on its front sidewith locating parts 2| against which, parallel to the axis of thefunnel, the projecting ends of the grid posts. OIWilBslU bear when themount is in position :for loading. These parts 2| are provided withslight recesses or grooves for receiving the wires Ill and facilitatingthe alignment. The funnel member and the mount are aligned with thecylindrical, bore IT in alignment with the opening 4 and the interior ofthe grid 1 when the mount is held with its end against the underside ofthe loading device and the projecting wires II] in the grooves 22.

With the funnel member I5 and the locating element supported in anysuitable manner as, for example, by bracket 25, the thermionic mount isheld in the assembling position shown in Figs. 4-6 with the locatingelement 20 resting upon the disc 4 and against the projecting ends II]of the posts or wires carrying the grids. The grooves 22 which areformed in the aligning parts 2| of the element 20 facilitate thelocation and positioning by forming positive bearing surfaces. Theelement 20 may also be provided with a projection 23 extending betweenthe projecting ends I6 of the grid posts or wires which also facilitatesthe location and positioning of the mounts against the funnel element.Preferably an auxiliary support 25', in the form of a V, is carried bythe bracket 25, against which the body of the mount rests during theloading.

The funnel element I5 is preferably supported at an angle of 115" fromthe horizontal plane inclined to the left of the loading operator orperpendicular to the horizontal plane depending upon the type of tubeconstruction. In the particular embodiment here shown, the funnelelement is supported at an angle of approximately 115 to the horizontal.of an angle supporting bracket member 26 fastened as indicated-at 21 toa supporting frame 28. The support '25 for the funnel I5 is formed of atwisted strip of metal and the end is attached to the upper-end of theangle member 26 by a screw 29. Thus the funnel I5 is supported with theplane of the slot I8 in the plane of the supporting member '26 and thefunnel may be adjusted to any desired position in that plane byadjusting the supporting arm 25 with respect to the fixed supporting arm26.

The loading or assembling operation is facilitated by impartingvibrations to the funnel I5 during the loading operation and in theparticular embodiment shown in Fig. 1 this vibration is imparted to thefunnel I5 by means of a vibrating means which imparts the vibration tothe angle support 26. The yibrating means is carried by a bracket 3|mounted upon the fioor or frame 28 and comprises an element 32 whichdirectly acts upon the support 26 to vibrate it and impart to theloading unit I5 vibrations with sufficient amplitudeand frequency toaccelerate the loading and assembling of the filaments II during theirpassage through the loading device and into and through the grid 1. Thisvibrating means '30 is diagrammatically illustrated for conveniencein'illustration and it comprises generally any electrical or othersuitable means for imparting a vibrating motion to the element 32 andhence to the support 26. In the modification of Fig.3a the vibratingmeans comprises electrical coils 30 mounted on a plate 26' carried atthe upper end of 26 and a hammer element 32 actuated by the coils. Itwill be understood that in Fig. 3a, the plates 26, the brace 25' and thefunnel I5 are rigidly connected together in any suitable manner, so thatvibrations of the plate 26' resulting from the blows of the hammer 32are transmitted to the funnel l5. For convenience of illustration themeans connecting the elements 26', 15 and 25 are not shown in thediagrammatic drawings.

The fine emission'filaments II are each provided with a supporting armand electrical con- This is effected by means nection 35 at one end andeach is loaded at its other end with a heavy terminal or weight 36.

The method in operation of assembling the emission filaments I I are asfollows:

A mount as shown in Figs, 4-6 is held against the funnel or the element20 with the cylindrical bore I11 properly aligned with respect to theopening 4' of the disc 4. This may be done by hand. With the mount thusheld firmly against the loading device an emission filament II isintroduced into the funnel whereupon the vibrating means 30 is set intooperation to impart the desired vibration to the loading device. Thisvibration causes the filament II quickly to feed itself downwardly intothe mount, the loaded end 36 falling by gravity during the shaking orvibrating operation through the opening 4 in the insulator disc 4 andthence downwardly through the interior of the grid 1. The lower disc 3is provided with an opening 3' in alignment with the opening 4' in'theupper disc and the loaded or weighted end 36 of the filament quicklyfinds its way through this opening '3', the vibration step'facilitatingthis operation. The right angle electrical connection 35 arrests thedownward movement of the filament when it reaches the disc 4. Thisconnection 35 easily finds the slot I8 through the flared opening at I8and follows the slot on down until it rests on the end of the mount.

The grid 1 is provided with a filament tensioning member 40 which is inthe form of an angle piece welded to one of the posts or wires If]intermediate its ends. It projects inwardly and laterally of the gridand is then turned to form a bend 40' crosswise of the plane ofthe gridwires, When the filament II is finally fastened at its ends the filamentassumes some such position as that indicated in Fig. 7, with the member40 engaging and tensioning the filament against vibration. In theassembling operation the mount is inclined to the left, looking at Fig.4, so that the weighted end 36 of the filament tends to follow the lefthand wire Ill downwardly as a guide past the member 40. The vibration ofthe loading device and the mount during the assembly operation and theinclination cause the loaded end 36 to dance past this member 40 whichin the conventional practice causes so much difliculty in the loadingoperation.

With the filament II introduced through the grid 1 as shown in Fig. 4,the electrical connections may be made in any suitable manner, and theseconnections are omitted from the drawings for convenience inillustration. The parts'35 and 36 serve as means for connecting thefilament in circuit. Only the mount comprising the discs 3 and 4 andintermediate parts is shown, but it is understood that the completedtube would include an envelope, a seal and the desired electricalconnections. The mount of the particular radio tube shown comprisesaglass button 42 (Fig. 3a) which forms a ready means by which the mountmay be held against the loading device with the fingers.

We claim:

l. The method of loading small direct emission filaments in miniaturethermionic devices comprising the steps of aligning the thermionicmounts with and holding them firmly against a loading device, feedingthefilaments to said loading device and applying a vibrating force to saidloading device during the loading operation.

2. The method of loading'direct emission filaments in mounts 'forthermionic devices comprising the steps of aligning the mounts withfunnel-shaped loading device having an elongated slot on one sidethereof and holding the mounts firmly against the loading device withthe funnel device in line with miniature grid elements of the mounts,feeding endwise to said funnel filaments having their lower ends loadedand angular electrical connections fastened to their upper ends, saidfunnel-shaped device having a slot on one side for the accommodation ofsaid electrical connections, and applying a vibrating force to saidfunnel-shaped device and the mounts after the filaments are fed to thefunnel device.

3. The method of loading direct emission filaments in mounts forthermionic devices comprising the steps of aligning the mounts with afunnel-shaped loading device having an elongated slot on one sidethereof and holding the mounts firmly against the loading device withthe latter in line with miniature grid elements of the mounts, feedingendwise to said funnel filaments having their lower ends weighted andelectrical connections fastened to their upper ends, said funnel-shapeddevice having an elongated slot on one side for the accommodation ofsaid electrical connections, and applying a vibrating force to saidfunnel-shaped device and the mounts after the filaments are fed to thefunnel device, said funnel device being supported with its axis inclinedto the vertical.

4. The method of loading direct emission filaments in mounts forthermionic devices comprising the steps of aligning the mounts with afunnel-shaped loading device having a slot on one side thereof andholding the mounts firmly against the loadingdevice with the latter inline with miniature grid elements of the mounts, feeding endwise to saidfunnel filaments having their lower ends weighted and angularconnections fastened to their upper ends, said funnelshaped devicehaving a slot on one side for the accommodation of said electricalconnections, and applying a vibrating force to said funnel-shaped deviceand the mounts after the filaments are fed to the funnel device, saidfunnel device being supported with its axis inclined to the vertical andaway from tensioning members disposed intermediate the ends of the gridswith the grid wires guiding the filaments to the desired locationswithin the grids.

5. The method of assembling filaments in miniature thermionic deviceswhich comprises the steps of feeding a filament through an orifice inthe mount assembly to one end of the miniature grid within which it isto be positioned and applying to said thermionic device a vibratingforce to facilitate the introduction of the filament into the grid.

6. The method of assembling direct emission filaments in mounts forthermionic devices which comprises the steps of holding themounts'inclined to the vertical, feeding the filaments endwise intoorifices in the upper ends of the inclined mounts and applying avibrating force to the mounts.

7. The method of assembling filamentary elements in miniature thermionicmounts which comprises the steps of introducing an end of an elementinto an orifice in the end of a mount and. applying a vibrating force tothe mount to cause the filament to feed itself into the mount.

8. The method of assembling filamentary elements into the grid parts ofminiature thermionic mounts which comprises the steps of loading thefilamentar elements with weights at one end, feeding the elementsendwise to the grid elements with the weighted ends down, and causingthe weighted filamentary elements to feed them selves downwardly intothe grid parts by the application of high frequency vibrations.

9. The method of assembling filamentary elementsinto the grid parts ofminiature thermionic mounts which comprises the steps of loading thefilamentary elements with weights at one end, feeding the elementsendwise to the grid elements with the weighted ends down, and incliningsaid grid elements to the vertical to cause the elements to follow agrid support wire as a guide.

10. The method of assembling filamentary elements into miniaturethermionic mounts which comprises the steps of fixedly supporting aloading device, successively holding the mounts against the loadingdevice in alignment therewith to receive the filaments, inserting thefilaments into the loading device and after filaments are fed to theloading device applying a vibrating force to said loading device.

11. A means for facilitating the assembly of filamentary elements intominiature thermionic mounts comprising a loading device with which themounts are to be aligned for the reception of the filamentary elementsand means for imparting to said loading device vibrations of the desiredfrequency and amplitude.

l2..A means for facilitating the assembly of filamentary elements intominiature thermionic mounts comprising a loading device with which themounts are to be aligned for the reception of the filamentary elementsand means for imparting to said loading device vibrations of the desiredfrequency and amplitude, said loading device being supported at an angleto the vertical.

13. A means for facilitating the assembly of filamentary elements intominiature thermionic mounts comprising a loading device with which themounts are to be aligned for the reception of the filamentary elementsand means for imparting to said loading device vibrations of the desiredfrequency and amplitude, said loading device having an interior which isfunnel-shaped at its lower end.

14. A means for facilitating the assembly of filamentary elements intominiature thermionic mounts comprising a loading device with which themounts are to be aligned for the reception of the filamentary elementsand means for imparting to said loading device vibrations of the desiredfrequency and amplitude, said loading device having an interior which isfunnel-shaped at its lower end and having a longitudinal slot in thewall thereof.

15. A means for facilitating the assembly of filamentary elements intominiature thermionic mounts comprising a loading device with which themounts are to be aligned for the reception of the filamentary elementsand means for imparting to said loading device vibrations of the desiredfrequency and amplitude, said loading device comprising an upper partfor the reception of the filamentary elements and a lower part having analigning and locating part against which the thermionic devices are heldduring the loading operation.

FRANK R. KEW. JOSEPH JAMES BANNON, JR.

